A couple major benefits of using Sandbag Trainers is they help build strength and stability. The contents of a sandbag trainer can be unstable and awkward to grip so you'll be working muscles you may not have expected. Small (up to 60lbs) and Large (up to 100lbs) trainers are available. You can fill them with sand, gravel or wood pellets. If you use fillers you can easily adjust the weight. We have 10lb, 20lb, 35lb and 40lb fillers available.